Marine Interpretation Message
Issued by NWS

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525
AGNT40 KWNM 010656
MIMATN

MARINE WEATHER DISCUSSION FOR N ATLANTIC OCEAN
NWS OCEAN PREDICTION CENTER WASHINGTON DC
256 AM EDT SUN MAY 1 2016

.FORECAST DISCUSSION: MAJOR FEATURES/WINDS/SEAS/SIGNIFICANT
.WEATHER FOR THE NORTH ATLANTIC OCEAN W OF 50W FROM 30N TO 50N.

OVER THE SHORT TERM...AS THE NEW 00Z MDLS ALL FCST A WEAK HIGH
PRES RIDGE TO PASS E ACRS THE WTRS TODAY THEY SHARE SMLR FCST
TIMING FOR A WARM FRONT TO PUSH NE OFF THE MID ATLC COAST LATE
TODAY...MOVE NE INTO THE SRN NT1 WTRS TONITE...THEN CONT NE ACRS
THE RMNG NT1 WTRS MON. LATE MON INTO EARLY MON NITE THE MDLS ALL
FCST A SLOWLY DVLPG SFC LOW ON THE FRONT TO CROSS THE NRN NT1
WTRS. VS THE MR SRN 00Z NAM/GEM...PREFER THE MR CONSISTENT NRN
TRACK OF THE 00Z GFS/UKMET/ECMWF FOR THIS LOW WHICH IS SPRTD BY
THE 00Z GEFS MEAN. IN RGRDS TO THE FCST GRADIENTS ASCD WITH THIS
FROPA...SMLR THE PREV FCST PACKAGE WL POPULATE OUR FCST WIND GRIDS
WITH THE REPRESENTATIVE 00Z GFS 10M BL WINDS FOR TODAY THRU MON
NITE...BOOSTED UP 10 PERCENT ON AVERAGE FM THE GULF STREAM SWD. SO
PER THESE WINDS SINCE THE 00Z GFS IS SLIGHTLY WEAKER THAN ITS PREV
RUNS...WL NOW REMOVE THE PREV NT1 GALES AND LIMIT ANY ASCD GALES
TO THE SSWLY GRADIENT TO ACRS THE NE MOST NT2 WTRS LATE MON (AND
EVEN WITH THESE GALES NOW HV ONLY LOW/MOD FCST CONFIDENCE AT
BEST).

IN THE LONG RANGE...LATE TUE INTO WED...VS ITS PREV 18Z RUN THE
00Z GFS HAS NOW FLIP-FLOPPED BACK TO FCSTG A WEAKER AND LESS
PROGRESSIVE FRONTAL WAVE TO TRACK NE ACRS THE CNTRL/NRN NT2 AND SE
NT1 WTRS WHICH IS BEST SPRTD BY THE 00Z GEM WITH BOTH MDLS CONTG
TO FCST SM GALE FORCE ASCD BL WINDS ACRS THE OUTER CNTRL/NE NT2
WTRS IN THEIR SSWLY GRADIENTS SE OF AN ASCD STNRY FRONT. THE 00Z
UKMET/ECMWF CONT TO FCST WEAKER SSWLY GRADIENTS TO DVLP. THEREFORE
AS A COMPROMISE WL TRANSITION TO POPULATING WITH A 50/50 BLEND OF
THE 00Z GFS 10M AND 00Z ECMWF BL WINDS ON TUE/TUE NITE.

THEN LATER IN THE LONG RANGE...WED INTO THU...THE 00Z GLOBAL MDLS
GNRLY AGREE THAT AN UPR L/W TROF WL DIG INTO THE ERN CONUS WITH
AN UPR LOW CLOSING OFF NR THE NRN MID ATLC COAST THU NITE. BUT DUE
TO THE MDLS RMNG INCONSISTENT WITH THEIR ASCD EMBEDDED S/W
TROFS...THEY CONT TO HV SIG RUN-TO-RUN DIFFERENCES IN HOW THE ASCD
SFC PATTERN WL DVLP. VS ITS PREV 18Z RUN...THE 00Z GFS FCSTS A
STRONGER S/W TROF TO ROTATE OFSHR LATE WED INTO THU AND AS A
RESULT NOW FCSTS A STRONGER SFC LOW TO MOV NE OFF THE N CAROLINA
COAST WED...TRACK NNE INTO THE NT1 WTRS WED NITE...THEN MOV INLD
MAINE LATE THU...WHICH IS SPRTD BEST BY THE SLIGHTLY MR
PROGRESSIVE 00Z GEM/ECMWF. THE 00Z UKMET IS ALSO SMLR TO THE 00Z
GFS ON WED...BUT THEN TRACKS ITS FCST LOW FURTHER W WED NITE/THU.
FOR NOW AGAIN AS A COMPROMISE WL POPULATE WITH A 50/50 BLEND OF
THE 00Z GFS 10M AND 00Z ECMWF BL WINDS ON WED/WED NITE. THEN ON
THU/THU NITE THE DISPARITY BTWN THE 00Z GLOBAL MDLS INCREASES. VS
ITS PREV 12Z RUN...THE 00Z ECMWF HAS NOW MADE A RADICAL CHANGE TO
A SIGLY MR PROGRESSIVE PATTERN. ON THE OTHER HAND THE 00Z GFS
REMAINS CONSISTENT IN FCSTG A NRLY VERTICALLY STACKED SFC LOW TO
CONSOLIDATE NR THE NRN MID ATLC COAST THU NITE. SO FOR NOW WITH
VERY LOW FCST CONFIDENCE...SINCE ITS SPRTD BY THE 00Z GEFS MEAN
(AND THE OLD 12Z ECENS MEAN) AND MR IN LINE WITH THE LATEST WPC
MEDIUM RANGE GUIDANCE...WL TRANSITION TO POPULATING WITH ALL 00Z
GFS 10M BL WINDS ON THU/THU NITE.

.SEAS...THE 00Z WAVEWATCH III HAS INITIALIZED SLIGHTLY BETTER
THAN THE 00Z ECMWF WAM. WITH THIS IN MIND AND SINCE THE 00Z GFS
WL BE FAVORED...WL POPULATE OUR FCST WAVE GRIDS WITH THE 00Z
WAVEWATCH III FOR TODAY THRU MON NITE. THEN SINCE A COMPROMISE 00Z
GFS/ECMWF SOLUTION WL BCM FAVORED...WL POPULATE WITH A 50/50 BLEND
OF THE TWO WAVE MDLS FOR TUE THRU WED NITE. THEN SINCE THE 00Z GFS
WL BCM FAVORED...WL TRANSITION BACK TO ALL 00Z WAVEWATCH III FCST
SEAS FOR THU/THU NITE.

.EXTRATROPICAL STORM SURGE GUIDANCE...N/A.

.WARNINGS...PRELIMINARY.

.NT1 NEW ENGLAND WATERS...
     NONE.

.NT2 MID ATLC WATERS...
.ANZ920...BALTIMORE CANYON TO THE GREAT SOUTH CHANNEL...
     GALE POSSIBLE WED NIGHT.
.ANZ905...THE GREAT SOUTH CHANNEL TO THE HAGUE LINE...
     GALE MON.
     GALE POSSIBLE WED NIGHT.
.ANZ910...EAST OF THE GREAT SOUTH CHANNEL AND SOUTH OF 39N...
     GALE MON.
     GALE POSSIBLE WED NIGHT.

$$

.FORECASTER VUKITS. OCEAN PREDICTION CENTER.



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